Patients with Hodgkin's disease, mycosis fungoides, lymphocytic lymphoma, and controls undergoing laparotomy for benign diseases will be studied. Concomitant studies will be done on blood mononuclear leukocytes and tumor or node cells. H3-thymidine incorporation by these two cell preparations will be measured in response to phytohemagglutinin, pokeweed mitogen and allogeneic leukocytes. The stimulatory capacity and macrophage function by both cell preparations in the mixed leukocyte reaction will also be tested. One-way stimulating cultures (using X-irradiation) between blood and tumor or node cells from the same test patients will also be undertaken. Relationships will be sought between the above data and (a) clinical stage, tumor histology and subsequent survival, (b) percentages of B and T cells among the lymphocytes under test, (c) absolute and functional serum thymosin levels when studied and (d) possible increased reactivity by hyporeactive cells when exogenous thymosin is added to the cultures. A major objective is to see if lymphocytes from tumors are monoclonal with restricted function or qualitatively and functionally polyclonal as would be expected from reactive lymphocytes. Through non-stimulation in the mixed leukocyte reaction and reactivity between autologous blood and tumor cells, new prognostically useful indicators may be identified. A role is also sought for thymic "hormone" for functional deficits of lymphocytes often associated with malignant lymphoma.